As an amateur you probably don't have enough context to know, but what you see on a superficial level of the product is probably about < 10% of the total engine

As an amateur you probably don't have enough context to know, but what you see on a superficial level of the product is probably about < 10% of the total engineering effort. Reddit awards, payments, ad analytics, SRE is probably 100+ engineers right there without even talking about the core experience, mobile app and security folks. The platforms that run 8 figure companies need tons of redundancy in both application code/infrastructure and people.